As a fellow newbie, I can tell you that the great folks on this site can provide a TON of information. But let me share a horror story on how NOT to do things:

After spending 12 years in the Army, I decided to get out and get a place where I could live for more than 6 months at a time. My fiance and I found 80 acres in North-Central Oklahoma which had a 3 acre pond that had gone dry in a drought and a half acre pond that stayed full even with cattle using it as a water hole. In part of the sale negotiations the real estate agent, who was also a banker at the bank that owned the property, said they had talked to a dozer company and the estimate was $3000-$5000 to remove the silt from the pond, making it on average 4 feet deeper than it was. We settled on the bank paying the first $2000 and we would pay the rest at closing. Work progressed on the pond and closing was getting close. Then suddenly, the dozer guy says "That is $5000 dollars, I'm done unless you want to spend more." Was he almost done with the pond. Not even close. I would estimate that he had only touched 10, maybe 20% of the whole thing. The bank wouldn't force him to finish (dozer guy owed bank a lot of money on loans), dozer guy wouldn't even talk to me (cost was an "estimate", not a "bid", and we got stuck with a partially cleared pond with no spillway (covered with piles of silt not spread out.) Pond is now filled up, looks great, but not nearly as deep as I had hoped. Average depth is probably 4-6 feet, with an area down by the dam that was cleared out more like 10-15 feet deep.

Morals of the story:
1. Talk to an expert. Talk to a couple of them. Find out as much as possible before starting (like you are now.)
2. Don't believe the first thing you hear.
3. Get it in writing. Avoid the "bid" vs. "estimate". Also, cheapest doesn't mean best. Often means more expensive to fix things that should have been done right the first time.
4. Do independant research. Look at the great books and articles listed around this site.
5. Finally, an unsolicited plug: SUBSCRIBE! This site and associated magazine

Shawn